Sample

/**
 * Copyright mattodesign ( http://wonderfl.net/user/mattodesign )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/9Ib3
 */

//練習
//Flash Math & Physics Design:ActionScript 3.0による数学・物理学表現[入門編]
//http://www.amazon.co.jp/Flash-Math-Physics-Design-3-0%E3%81%AB%E3%82%88%E3%82%8B%E6%95%B0%E5%AD%A6%E3%83%BB%E7%89%A9%E7%90%86%E5%AD%A6%E8%A1%A8%E7%8F%BE/dp/4797351411


package 
{
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.utils.Timer;
	import flash.events.TimerEvent;
	
	public class Main extends Sprite {
		var circle:Sprite;
		var ookisa:Number = 0;
		var timer:Timer;
		
		//コンストラクタ
		public function Main():void {
			//stage初期化
			if (stage) init();
			else addEventListener(Event.ADDED_TO_STAGE, init);
			//circle作成
			circle = new Sprite();
			circle.graphics.beginFill(0x000000);
			circle.graphics.drawCircle(0, 0, 50);
			addChild(circle);
			//1秒間に30回loopを実行
			timer = new Timer(33);
			timer.addEventListener(TimerEvent.TIMER, loop);
			timer.start();
			}
		
		function loop(event:TimerEvent):void {
			ookisa += 0.05;
			if (ookisa > 10) {
				ookisa = 0;
				}
			circle.x = this.mouseX;
			circle.y = this.mouseY;
			circle.scaleX = circle.scaleY = ookisa;
			}
		
		private function init(e:Event = null):void {
			removeEventListener(Event.ADDED_TO_STAGE, init);
			// entry point
			}
		
	}
	
}